Thin wall catheter and method of placing same
Methods and apparatus for introducing diagnostic and/or therapeutic agents and devices within a mammalian body are disclosed. One disclosed apparatus comprises a sheath having a proximate end, a distal end and a lumen extending therebetween. An articulator is disposed in the lumen of the sheath. A distal portion of the sheath is detachably attached to a distal portion of the articulator at a joint. A separator capable of severing the joint is also provided. One disclosed method comprises the step of providing a device comprising a sheath disposed about an articulator with a distal portion of the sheath being fixed to the articulator at a joint. The device is inserted into a lumen of a body. The joint is severed and the articulator is withdrawn from the sheath.
The present disclosure relates generally to the introduction of diagnostic and/or therapeutic agents and devices within a mammalian body.
BACKGROUND OF THE INVENTIONThe present disclosure relates generally to the field of introducing diagnostic and therapeutic agents and devices within the human body. By placing a hollow tube in a patient's body a surgeon may gain access to difficult to reach areas of the anatomy. The patient has great benefit from not having large muscles and nerves severed by the surgeon to gain access to the afflicted area. This is sometimes referred to minimally invasive forms of surgery.
The catheter was invented 95 years ago by Charles Russell Bard for the treatment of urinary discomfort. Since that time, many special purpose catheters have been developed. A great deal of engineering effort has gone into making catheters rigid and resistant to kinking. This rigidity and kink resistance aids in the ability to advance the catheter through the vasculature. A very stiff catheter may have a difficult time following in the tortuous conduits of the human vasculature system without tending to straighten the vessels to conform to the tubing. Additionally, the presence of the catheter in the vasculature restricts blood flow. The stiffness of the catheter may cause damage to the walls of blood vessels. An example of this adverse effect is a clot that can travel to the lungs and cause death by pulmonary embolism. Pulmonary embolism is an obstruction of a blood vessel in the lungs which blocks a coronary artery. According to the American Heart Association, an estimated 600,000 Americans develop pulmonary embolisms annually.
Catheters are often manufactured with rigid walls in order to facilitate pushing of the catheter over the guidewire. Physicians sometimes complain that forcing catheters with heavy walls through the veins and arteries cause damage to the vascular endothelium. In addition, clots can form at the tips of these catheters.
Stylets and guidewires are used to control the manner in which intravascular leads and catheters are introduced into the veins or arteries of the body. Conventional intravascular procedures typically involve an initial step of introducing and routing a guidewire through a patient's vascular system to provide a rail or track along which additional devices may be introduced. Once a guidewire is in place, a catheter is routed over at least a portion of the guidewire to provide a larger opening into the vein or artery and sometimes to protect the inside walls of the vessels along the route of the guidewire. With the sheath in place, the guidewire may be removed or may remain in place as additional devices such as intravascular leads and catheters are introduced into the patient's vascular system.
In contrast to the guidewire which serves as a track over which other devices are routed, a stylet is used within an internal lumen of a device both to push that device through the vascular system and to steer the device as it is being pushed. Although some devices are designed to steer themselves using internal pull wires, almost all leads, most catheters and some guidewires have an inner channel or lumen into which a stylet is inserted. In addition to pushing the device through the vascular system by engaging the distal end of the device, the stylet also serves to deflect the distal end of the device so as to steer the distal end through the vascular system. Unlike the lead, catheter or guidewire, which has a distal region that is flexible and floppy, the stylet must be stiffer and more rigid so as to enable the stylet to push the lead or catheter through the patient's vascular system. Stylets have been provided with steerable technology, such as described in applicants own U.S. application Ser. No. 09/934,245, filed Aug. 21, 2001, the contents of which are herein incorporated by reference. Further, stylets have been provided with adjustable stiffness technology, as described in applicant's own U.S. application Ser. No. 09/843,040, filed Apr. 25, 2001, the contents of which are herein incorporated by reference. Such steerable and adjustable technologies are useful for guiding the stylet and/or device through the vascular system.
The more control and flexibility an operator has over a device, the easier it is to operate that device. In the case of stylets, the physical demands of engaging the distal end of a lumen of a device so as to push that device through the vascular system impose constraints on the beam strength of the device that are much different than the constraints encountered for a guidewire, catheter or lead. Most guidewires are constructed from a tapered core wire with a coiled round wire wrapped around this tapered core wire in order to achieve the necessary flexibility in the distal region of the guidewire. Stylets, on the other hand, are generally constructed of a solid wire of uniform diameter without any coils around this wire in order to achieve the necessary strength and rigidity required over the entire length of the device so as to function as a stylet.
The flexibility of the stylet, as well as its ability to appropriately guide the device through a vascular channel is currently compromised by its engagement with the distal end of the device. For example, the stylet may currently be retained within the distal end of a catheter. Therefore, when the stylet is guided, such as by steering it, it must articulate within the catheter. In such a system the catheter will also articulate, which produces greater stress on the steerable portion of the stylet and reduces the ability of the device to be steered within the vascular system. Therefore, a need exists for a device that couples a stylet with a medical device such as a catheter in such a way that the stylet's ability to guide the device through the body is not compromised, yet which allows the stylet to be detached from the device and retracted from the body, leaving the device in place.
SUMMARY OF THE INVENTIONThe present disclosure relates generally to the introduction of diagnostic and/or therapeutic agents and devices within the human body. A device in accordance with the present invention comprises the articulator and a sheath. In some advantageous embodiments, the articulator is a steerable articulator. Also in some advantageous embodiments, the articulator comprises one or more adjustable stiffness sections. In one aspect of the present invention, the sheath comprises a relatively thin wall. This thin wall, maximizes the inner diameter of the sheath allowing larger objects to pass through a lumen defined by the sheath.
A distal portion of the sheath is attached to a distal portion if the articulator. The sheath is carried to the site of therapy by the articulator and then released by the motion of sliding tubular member surrounding the articulator. The sheath may be constructed from polymer materials that are proven to be hemo-compatible for limited exposure, prolonged exposure and/or permanent contact. Limited exposure generally means that the human body is exposed to the device for less than 24 hours. Prolonged exposure generally means that the human body is exposed to the device for between 24 hours and 30 days. Permanent contact generally means that the human body is exposed to the device for between 24 hours and 30 days. A proximal portion of the articulator resides loose within a lumen defined by the sheath to allow the sheath and the articulator to flex independently.
The sheath differs from existing catheters by virtue of a thin wall and flexibility. The thin wall allows blood to flow more easily around and along the length of the sheath. The sheath may be soft enough that the arterial pressure will collapse the thin wall causing little occlusion to the blood flow. The sheath may remain collapsed until a secondary device is passed through the sheath lumen. The lumen will open to allow the device to pass but will still allow maximum blood flow. A sheath in accordance with the present invention may have a hoop strength that is selected so that the catheter will collapse while it is disposed within a blood vessel. The blood pressure causes the sheath to collapse. The blood pressure may be for example 60 millimeters of mercury.
In some embodiments, the sheath may comprise a distal section that is of a different durometer than other portions of the sheath. This different durometer section may function to hold the distal end proximate a target location in the body. This different durometer section may also function to strengthen the connection between the sheath and the articulator. The different durometer section may be an elongated section of a few millimeters comprising a harder material. The different durometer section may comprise an O-ring. A lure fitting may be coupled to a proximate end of the sheath.
The sheath may comprise a straight tube as one example. The sheath may comprise a tube with two or more lumens as another example. When this is the case, the articulator may be placed in the smaller of the two lumens. The sheath may be pulled to the target site by the articulator. The articulator may then be retracted a distance to allow the distal catheter tube to collapse when the physician inserts another medical device into the larger of the two lumens. In some cases, the articulator may be partially retracted without drawing the articulator completely out of the lumen. When this is the case, the articulator need only be retracted far enough so as not to interfere with the other devices being passed through the sheath.
In some embodiments, the invention relates to a device that includes a medical device comprising a sheath and the articulator. The articulator and the sheath may be operatively connected proximate their distal ends. A deployment actuator may be provided to detach the sheath and the articulator. In some embodiments, the deployment actuator comprises a tube with a length longer than that of the sheath. When the tube is pushed in the distal direction it breaks a bond between the articulator and the sheath. In such embodiments, the articulator retains its ability to guide the device through the body. The invention also includes methods of placing diagnostic and therapeutic agents and devices inside a body.
The deployment apparatus described above may allow for a sheath with a thinner wall than conventional catheters because the stiffness of the articulator allows the sheath to be placed without relying on its own rigidity. Such a thin wall sheath is advantageous because it allows for maximization of the lumen diameter to allow for the passage of larger devices through the sheath given the same outside diameter size. The larger devices passing through a protective sheath may cause less vascular disruption than the larger device being pushed through the vessel by itself. Such embodiments are useful for reducing damage to the vascular system during intravascular procedures. In many procedures done today, the larger device (e.g., PCTA balloon catheter) is pushed over a guidewire. PCTA catheters are typically quite stiff and have uneven surfaces that may cause disruption to the vascular system.
BRIEF DESCRIPTION OF THE DRAWINGS
The following detailed description should be read with reference to the drawings, in which like elements in different drawings are numbered identically. The drawings, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of the invention. Examples of constructions, materials, dimensions, and manufacturing processes are provided for selected elements. All other elements employ that which is known to those of skill in the field of the invention. Those skilled in the art will recognize that many of the examples provided have suitable alternatives that can be utilized.
Device 10 also may include an articulator 30 useful for the placement of the sheath 20 within a vascular system and having a proximal end 32 and a distal end 34. The articulator 30 may be coated with a lubricious coating. In some embodiments, the articulator 30 comprises one or more steerable poritons and/or one or more adjustable stiffness portions.
Device 10 may also include a deployment actuator 40 useful for detaching the sheath 20 and the articulator 30 once the device 10 is placed within the vascular system. The detachment of sheath 20 and articulator 30 allows the articulator 30 to be retracted from the body, leaving the sheath 20 in place. Thereafter, other tools may be placed into the lumen of the sheath 20. Deployment actuator 40 may be any device capable of detaching sheath 20 and articulator 30 from each other, and may contain a lubricous coating on its outside and/or inside surfaces.
In some embodiments, the deployment actuator 40 may comprise a tube 42 having a proximal end 44 and a distal end 46. Tube 42 may comprise any material capable of flexing though a vascular system and of transmitting axial force sufficient to detach sheath 20 from articulator 30. In some embodiments, tube 42 comprises a polymeric material such as polyurethane and/or polytetrafluoroethylene.
Tube 42 may be allowed to slide axially between the sheath 20 and the articulator 30 as shown in
Sheath 20 and articulator 30 may be operatively coupled together in any fashion. For example, sheath 20 and articulator 30 may be operatively coupled together by a vacuum seal, adhesive, chemical bond, and/or mechanical linkage. An embodiment of a vacuum seal is shown in
Such a deployment system allows for the catheter to have a thin wall compared to conventional catheters, thereby providing a larger lumen 50 as shown in
As mentioned above, the deployment actuator 40 may be used with an articulator 30 which has steerable technology, as shown in
Also as mentioned above, the deployment actuator 40 may be combined with an adjustable stiffness articulator 30, as shown in
The present invention also includes a method of placing a medical device inside a body. In some embodiments, the method includes the steps of providing a device 10 having a medical device 12, such as a sheath 20, having a proximate end and a distal end, and an articulator 30 having a proximate end 32 and a distal end 34. The articulator 30 and the medical device 12 may be operatively connected proximate their distal ends. Further, a deployment actuator 40, such as a tube 42, may be provided. In some embodiments, an incision is made and the device 10 is inserted through the incision into a lumen of a mammalian body and routed through the body until in reaches a desired location. When it is desired to retract the articulator 30 while leaving the sheath 20 in place, they may be separated by applying an axial force to the deployment actuator 40 in either the distal and/or proximal directions. Thereafter, deployment tube 40 and articulator 30 may be retracted from the body.
First wire 108 comprises a wall 126 defining a lumen 122. In the embodiment of
Device 300 may be used to access remote regions of vasculature 348 of patient 340 to facilitate various medical procedures. For example, device 300 may be used to deliver diagnostic or therapeutic agents to target sites within the vasculature 348 of patient 340. By way of another example, device 300 may be used to deliver diagnostic or therapeutic devices to target sites within the vasculature 348 of patient 340.
It is contemplated that device 300 may be used in conjunction with an intravascular catheter to perform percutaneous transluminal coronary angioplasty (PCTA). When this is the case, the device may be advanced through the patient's vasculature until its distal tip is located proximate a restriction in a diseased vessel. In many cases, the device's path through the vascular system will be tortuous, requiring the device to change direction many times. Once the device is positioned, articulator 302 may be withdrawn from lumen 328 and a balloon catheter may be advanced into lumen 328 of device 300. The balloon catheter may be urged distally until a balloon fixed near the distal end of the catheter is centered on the restriction in the diseased vessel. The balloon may then be inflated to open the restriction. It is important to note that PTCA is just one example of the many procedures that may be facilitated by device 300.
A device in accordance with the present invention may also be use to facilitate endoscopic retrograde cholangio-pancreaticography (ERCP). ERCP procedures are often used when diagnosing and treating abnormal pathologies within the bile duct and the pancreatic duct. During such a procedure, device 300 may be inserted into a patients mouth guided through the patient's alimentary tract or canal until the distal end of the device is proximate the papilla of vater leading to the bile duct and the pancreatic duct. The device may then be guided through the orifice to the papilla of vater (located between the sphincter of oddi) leading to the bile duct and the pancreatic duct. The device may be advanced until the distal end of the catheter is positioned in a desired location. The wire may then be withdrawn from the lumen of the sheath. The sheath may be used to deliver fluoroscopic fluid to the bile duct and the pancreatic duct in order to diagnose pathological changes. A catheter may be advanced through the sheath. The catheter may also be used to take biopsies, extract stones or insert stents to provide for an unobstructed bile or pancreatic flow. Once the catheter is properly positioned, the sheath may help to maintain the position of the catheter during these procedures.
In
In some methods in accordance with the present invention, articulator 302 and sheath 304 of device 300 are advanced into the vasculature 348 together. Once the distal end of sheath 304 is proximate a target site the connection between articulator 302 and sheath 304 may be severed. When this is the case, articulator 302 will be slidingly disposed within lumen 328 of sheath 304. Articulator 302 may then be withdrawn from lumen 328 of sheath 304.
First wire 508 comprises a wall 526 defining a lumen 522. In the embodiment of
In the embodiment of
Sheath 704 may be formed, for example, using an extrusion process. Intermediate segment 766 of sheath 704 may comprise a mixture of the materials of distal segment 762 and proximal segment 764 to promote a strong bond between distal segment 762 and proximal segment 764. Proximal segment 764 of sheath 704 may have a hoop strength that is selected such that sheath 704 will collapse while it is disposed within a blood vessel. The blood pressure causes the sheath to collapse. The blood pressure may be for example 60 millimeters of mercury. The relatively thin, flexible wall of sheath 704 allows blood to flow more easily around and along the length of sheath 704. The wall of sheath 704 is soft enough that the arterial pressure will collapse the thin wall causing little occlusion to the blood flow. The sheath may remain collapsed until a secondary device is passed through the sheath lumen 728. The lumen will open to allow the device to pass but will still allow maximum blood flow.
First wire 908 comprises a wall 926 defining a lumen 922. In the embodiment of
First wire 908 comprises a wall 926 defining a lumen 922. In the embodiment of
In the embodiment of
A second hub 1070 is fixed to first wire 1008 proximate it's proximal end. Second hub 1070 includes a luer fitting 1070 that may be used to connect lumen 1022 of first wire 1008 to other devices. In the embodiment of
In some methods in accordance with the present invention, a source of relatively low pressure (e.g., a vacuum source) may be used to selectively couple sheath 1004 to articulator 1002. For example, vacuum source 1090 may be used to make the internal pressure within the lumen of first wire 1008 lower than the external pressure outside of sheath 1004. This causes the external pressure to urge sheath 1004 against first wire 1008 of articulator 1002.
Numerous characteristics and advantages of the invention covered by this document have been set forth in the foregoing description. It will be understood, however, that this disclosure is, in many respects, only illustrative. Changes may be made in details, particularly in matters of shape, size and ordering of steps without exceeding the scope of the invention.
Claims
1. An apparatus, comprising:
- a sheath having a proximate end, a distal end and a lumen extending therebetween;
- an articulator disposed in the lumen of the sheath;
- a distal portion of sheath being detachably attached to a distal portion of the articulator at a joint; and
- a separator capable of severing the joint.
2. The system of claim 1, wherein the joint comprises an adhesive.
3. The system of claim 2, wherein the adhesive comprises a cyanoacrylate adhesive.
4. The system of claim 2, wherein the adhesive comprises a silicone adhesive.
5. The system of claim 2, wherein the adhesive comprises polyethylene glycol.
6. The system of claim 1, wherein the joint comprises a solvent welded bond.
7. The system of claim 1, wherein the joint comprises a thermally welded bond.
8. The system of claim 1, wherein the joint comprises a chemical bond.
9. The system of claim 1, wherein the joint comprises a mechanical linkage.
10. The system of claim 1, wherein the articulator is steerable.
11. The system of claim 1, wherein the separator comprises a tube.
12. The system of claim 1, wherein the separator comprises a wire disposed within a lumen of the tube.
13. The system of claim 12, wherein the wire extends proximally beyond a proximal end of the tube.
14. The system of claim 12, wherein the wire extends distally beyond a distal end of the tube.
15. The system of claim 1, wherein the separator is actuated at a proximate end thereof.
16. The system of claim 1, wherein a portion of the distal end of the deployment actuator extends beyond a portion of the distal end of the sheath, and a portion of the distal end of the articulator extends beyond a portion of the distal end of deployment actuator.
17. The system of claim 1, wherein the sheath comprises a lubricous coating on an outside surface thereof.
18. The system of claim 1, wherein the sheath comprises an anti-thrombic coating on an outside surface thereof.
19. The system of claim 1, wherein the sheath comprises a lubricous coating on an inside surface thereof.
20. The system of claim 1, wherein a distal region of the articulator has adjustable lateral stiffness.
21. The system of claim 1, wherein a distal region of the articulator is capable of a first shape having a first lateral stiffness and a second shape having a second lateral stiffness.
22. The system of claim 1, wherein the sheath has a lateral stiffness that is less than a lateral stiffness of the articulator.
23. The system of claim 1, wherein the sheath has a hoop strength selected such that a pressure within the body lumen causes the sheath to collapse.
24. A method comprising the steps of:
- providing a device comprising a sheath disposed about an articulator with a distal portion of the sheath being fixed to the articulator at a joint;
- inserting the device into a lumen of a body;
- severing the joint; and
- withdrawing the articulator from the sheath.
25. The method of claim 24, wherein the step of severing the joint comprises the step of applying an axial force to a deployment actuator.
26. The method of claim 25, wherein the axial force is applied to the deployment actuator in a distal direction.
27. The method of claim 24, wherein the deployment actuator comprises a tube.
28. A device comprising:
- an articulator having a proximate end and a distal end;
- a sheath having a proximate end and a distal end;
- a distal portion sheath being detachably attached to a distal portion of the articulator at a joint; and
- a separator capable of detaching the sheath from articulator.
29. A sheath comprising:
- a first wall defining a first lumen;
- a second wall defining a second lumen;
- the second wall being substantially disposed within the first lumen;
- the first wall being folded to form at least one flap;
- the at least one flap being wrapped around the second wall.
30. An apparatus comprising:
- a sheath having a proximate end, a distal end and a lumen extending therebetween;
- an articulator disposed in the lumen of the sheath;
- an internal pressure within a lumen of the articulator being lower than an external pressure outside of the sheath; and
- the external pressure urging the sheath against the articulator for operatively connecting the sheath and the articulator.
Type: Application
Filed: Feb 15, 2005
Publication Date: Aug 17, 2006
Inventors: Gregory Townsend (Plymouth, MN), Thomas Soukup (Plymouth, MN)
Application Number: 11/058,685
International Classification: A61M 31/00 (20060101);